Abstract: A solid state electronically steerable antenna can be generated from a sheet of semiconductor material by forming a pattern of localised plasma regions in the sheet, either by injecting carriers into, or by generating carriers in, those localised regions. A suitable solid state plasma antenna can be made from a silicon wafer (10) by first thermally oxidising the surfaces and subjecting the wafer (10) to a high temperature stabilisation process to improve the stoichiometry at the silicon/silica interface, and optionally also performing a low-temperature bake in a gas mixture including hydrogen. This produces a wafer (10) with a long minority carrier lifetime. Regions of the wafer (10) in which plasma may be generated are then defined by reticulation to form isolated regions with high minority carrier lifetime. The resulting discrete regions may be of a size less than 1 mm, for example 0.3 mm.

Abstract: Apparatus for providing a controllable signal delay along a transmission line, which apparatus comprises a transmission line conductor on a dielectric medium comprised wholly or partially or a semiconductor material, and adjacent periodically separated electromagnetically-coupled elements, the coupling between the elements and the transmission line conductor being controllable through photonic and/or electrical injection of electrical carriers into the dielectric medium, whereby the apparatus is such as to enable control of the velocity of electromagnetic propagation along the transmission line and thereby through the apparatus.